In offshore production well systems, it is desirable to be able to quickly and effectively reconnect a piping string to a subsea wellhead. One of the primary problems which must be overcome in so doing, however, is the difficulty in creating an effective seal between the riser and the casing in the subsea wellhead. One of the seals that has been utilized in subsea connections is a metal-to-metal type seal.
The metal-to-metal type seal, to be effective, requires that a high compressive force be placed on it. The mechanisms previously used in connection with the metal-to-metal seal have been complicated and cumbersome and have not provided the desired degree of sealing between the riser and the subsea casing. As a result, the remote latching and sealing of the tie-back string to the wellhead has gone neither as smoothly, nor as quickly, as desired.
Accordingly, it is principal object of the present invention to remotely latch and seal a tie-back string to a production wellhead.
Another object of this invention is to remotely latch and seal a tie-back string to a production wellhead quickly and efficiently.
A further object of this invention is to apply hydraulic compressive force to a metal-to-metal type seal and to thereafter mechanically retain the applied compressive force.